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Abstract

Introduction: Retrohepatic vena cava (RVC) injuries are among the most lethal of injuries, often leading to exsanguination while vena cava repair is attempted. One well known yet seldom studied method of controlling RVC hemorrhage is the atriocaval shunt. Methods: Four female Yorkshire swine (30-40kg) were anesthetized, intubated, and underwent placement of femoral and pulmonary arterial catheters for continuous hemodynamic monitoring. After laparotomy and sternotomy, swine were shunted with 28Fr thoracostomy tubes. Shunts were secured in place with a right atrial appendage purse string suture and umbilical tape around the infracardiac and infrahepatic IVC. Swine were actively resuscitated with IV fluids while hemodynamic parameters, resuscitation volumes, and blood loss were measured for up to 4 hours before animals were euthanized. Results: Prior to shunting, the mean heart rate (HR), mean arterial pressure (MAP), and cardiac output (CO) were 102 ± 9 bpm, 65 ± 7 mmHg, and 4 ± 1 L/min, respectively. Immediately following shunt placement (n=4; mean EBL, 889 ± 208cc), shock became physiologically evident in measured parameters: HR 122 ± 34 bpm, MAP 36 ± 10 mmHg, and CO 3 ± 1 L/min. Two swine died after 11 and 14 minutes (IVF, 1800 ± 707cc; EBL, 912 ± 52cc) and two survived 2 hours after shunting (IVF, 3400 ± 1697cc; EBL, 865 ± 354cc). When compared to pre-shunt values, animals surviving 2 hours after shunting had decreased mean arterial pressures (65.3 ± 6.5 vs. 36.5 ± 7.8 mmHg; p=0.008) and decreased cardiac output (4.0 ± 1.1 vs. 1.6 ± 1 L/min; p=0.04). One of 4 (25%) swine survived the entire 4 hour study period following shunt placement (IVF, 4600cc; EBL, 1115cc) and was euthanized Conclusions: Despite normal pre-shunt hemodynamic parameters and the absence of a RVC injury, only one swine survived 4 hours after atriocaval shunting. While further study is warranted, our results highlight the profound physiologic compromise caused by the atriocaval shunting procedure itself